Method for forming thin film pattern and flat display device having the same

ABSTRACT

The present disclosure is a method for forming a thin film pattern to form a micron-pattern and a flat display device having the same. The method for forming a thin film pattern includes the steps of forming first to third thin film layers on a substrate in succession, forming a first photoresist pattern on the third thin film layer, patterning the second and third thin film layers using the first photoresist pattern as a mask to form first and second thin film mask pattern having line widths different from each other, forming a second photoresist pattern at a region where the first and second thin film mask patterns do not overlap positioned between the first thin film layer and the second thin film mask pattern, removing the first and second thin film mask patterns, and patterning the first thin film layer using the second photoresist pattern as a mask.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the Patent Korean Application No.10-2010-0055335, filed on Jun. 11, 2010, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to a method for forming a thin filmpattern to form a micron-pattern and a flat display device having thesame.

2. Discussion of the Related Art

Recently, the display device market is rapidly changing centered on theflat display devices which are becoming easier to fabricate lighter andlarger sized display devices. Flat display devices include liquidcrystal display devices (LCD), plasma display panels (PDP), organicelectro luminescence display devices (OLED), and so on.

A plurality of thin film patterns in the flat display device are formedthrough a thin film deposition step, a photolithography step having anexposure and development step, and a mask step having an etching stepand a photoresist removing step.

A photoresist pattern formed in the photolithography step has a minimumline width of about 4 μm, and about 3 μm of a minimum distance betweenthe photoresist patterns. The thin film pattern formed by etching usingthe photoresist pattern has a minimum line width of about 3 μm, andabout 4 μm of a minimum distance between the thin film patterns.Therefore, the resolution of forming the thin film pattern for a belowthe minimum line width of the thin film pattern is difficult.

SUMMARY OF THE DISCLOSURE

Accordingly, the present disclosure is directed to a method for forminga thin film pattern and a flat display device having the same.

An object of the present disclosure is to provide a method for forming athin film pattern which enables to form a micron-pattern and a flatdisplay device having the same.

Additional advantages, objects, and features of the disclosure will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thedisclosure. The objectives and other advantages of the disclosure may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, amethod for forming a thin film pattern includes the steps of formingfirst to third thin film layers on a substrate in succession, forming afirst photoresist pattern on the third thin film layer, patterning thesecond and third thin film layers by using the first photoresist patternas a mask to form first and second thin film mask patterns having linewidths different from each other, forming a second photoresist patternat a region positioned between the first thin film layer and the secondthin film mask pattern where the first and second thin film maskpatterns do not overlap with each other, removing the first and secondthin film mask patterns, and patterning the first thin film layer byusing the second photoresist pattern as a mask, to form a thin filmpattern.

In this instance, the second thin film layer is formed of an inorganicinsulating film or a columnar crystal group material, and the third thinfilm layer is formed of a non-transparent material which shields alight.

In detail, the columnar crystal group material is molybdenum.

In the meantime, the first thin film mask pattern has an obtuse orrectangular taper angle.

And, the step of forming a second photoresist pattern includes the stepsof forming second photoresist pattern on the substrate having the firstand second thin film mask pattern formed thereon to cover a side of thefirst thin film mask pattern and the first thin film layer, and exposingand developing the first photoresist pattern and the second photoresistpattern to remove the first photoresist pattern and to form the secondphotoresist pattern.

In another aspect of the present disclosure, a flat display deviceincludes a plurality of thin film patterns spaced away by a firstdistance from one another, each of the thin film patterns including twothin film patterns, wherein the two thin film patterns have line widthsformed the same with each other and spaced away by a second distancefrom each other.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIGS. 1A to 1G illustrate sections showing the steps of a method forforming a thin film pattern in accordance with an exemplary embodimentof the present disclosure.

FIG. 2 illustrates a plan view of a thin film transistor substratehaving a thin film pattern of an exemplary embodiment applied thereto.

FIG. 3 illustrates a section of the thin film transistor substrate cutacross the line I-I in FIG. 1.

FIGS. 4A and 4B illustrate a plan view and a sectional view showing anexemplary method for forming the gate metal pattern shown in FIGS. 2 and3.

FIGS. 5A to 5F illustrate sections showing the steps of an exemplarymethod for forming the gate metal pattern shown in FIGS. 2 and 3, indetail.

FIGS. 6A and 6B illustrate a plan view and a sectional view showing anexemplary method for forming the semiconductor pattern and the datametal pattern shown in FIGS. 2 and 3.

FIGS. 7A and 7B illustrate a plan view and a sectional view showing anexemplary method for forming the protective film having the pixelcontact hole and the common contact hole shown in FIGS. 2 and 3.

FIGS. 8A and 8B illustrate a plan view and a sectional view showing anexemplary method for forming the transparent conductive pattern shown inFIGS. 2 and 3.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to the specific embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

FIGS. 1A to 1G illustrate sections showing the steps of a method forforming a thin film pattern in accordance with an exemplary embodimentof the present disclosure.

Referring to FIG. 1A, first to third thin film layers 152, 154, and 156are stacked on a substrate 101, in succession.

The first thin film layer 152, a material layer of the thin film patternto be formed on the substrate 101, may be formed of a metal, aninsulating film, or a semiconductor layer.

The second thin film layer 154 may be formed of a material which formsan obtuse or rectangular taper angle θ after etching process. In detail,the second thin film layer 154 may be formed of an inorganic insulatingfilm, such as SiNx or SiOx, or a columnar crystal group metal, such asmolybdenum.

The third thin film layer 156 may be formed of a non-transparentmaterial, for an example, nickel Ni, which shields a light incident onphotoresist at the time of exposure.

Then, referring to FIG. 1B, after coating a first photoresist on thethird thin film layer 156, a first photoresist pattern 158 may be formedby exposure and development. After etching the third thin film layer 156by using the first photoresist pattern 158 as a mask, the second thinfilm layer 154 may be etched, to form first and second thin film maskpatterns 164 and 166. The first thin film mask pattern 164 may be formedto have a line width smaller than a line width of the second thin filmmask pattern 166. A distance Sd1 between one side of the first thin filmmask pattern 164 and one side of the second thin film mask pattern 166may be the same with a distance Sd2 between the other side of the firstthin film mask pattern 164 and the other side of the second thin filmmask pattern 166. In this instance, depending on an extent of etching ofthe second thin film layer, the distance Sd1 between one side of thefirst thin film mask pattern 164 and one side of the second thin filmmask pattern 166 and the distance Sd2 between the other side of thefirst thin film mask pattern 164 and the other side of the second thinfilm mask pattern 166 vary. That is, an etching time period on thesecond thin film layer may be relatively prolonged or shortened, anetching amount of the second thin film layer may increase or deceaserelatively, the distance Sd1 between one side of the first thin filmmask pattern 164 and one side of the second thin film mask pattern 166and the distance Sd2 between the other side of the first thin film maskpattern 164 and the other side of the second thin film mask pattern 166become relatively longer or shorter.

In the meantime, the distance Sd1 between one side of the first thinfilm mask pattern 164 and one side of the second thin film mask pattern166 and the distance Sd2 between the other side of the first thin filmmask pattern 164 and the other side of the second thin film mask pattern166 may vary a line width of the second photoresist pattern.

And, the taper angle θ of the first thin film mask pattern 164 may beformed to be an obtuse angle or a right-angle. In detail, at the time ofetching the second thin film layer of inorganic insulating film, if acontent of an etch gas of SF₆ is increased greater than a content (about1500 sccm) of the etch gas of SF₆ at which the taper angle of the secondthin film layer may be formed to be an acute angle, the taper angle θ ofthe first thin film layer is formed to be an obtuse angle or a rightangle. If the second thin film layer 154 of the columnar crystal groupmaterial which has an excellent traveling straight characteristic isetched, the taper angle θ of the first thin film mask pattern 164 maybecome a right angle.

Then, referring to FIG. 1C, second photoresist 162 may be coated betweenthe first and second thin film mask patterns 164 and 166. In thisinstance, since the second photoresist 162 is coated on the substrate101 in a liquid state, the second photoresist 162 may also be coated ona side of the first thin film mask pattern 164 which has an invertedstep from the second thin film mask pattern 166. That is, the secondphotoresist 162 may be formed to cover the sides of the first thin filmmask pattern 164 and the first thin film layer 152 exposed between thefirst thin film mask patterns 164. In this instance, a minimum height ofthe second photoresist 162 may be the same with a height of the firstthin film mask pattern 164.

Then, referring to FIG. 1D, the first photoresist pattern 158 may beremoved by full surface exposure and development, and, since the secondthin film mask pattern 166 of a non-transparent material is used as amask in exposure, the second photoresist 162 under the second thin filmmask pattern 166 is patterned by exposure and development to form asecond photoresist pattern 168. That is, the second photoresist pattern168 may be formed at a region positioned between the first thin filmlayer 152 and the second thin film mask pattern 166 at which the firstand second thin film mask patterns 164 and 166 do not overlap with eachother. A sum of line widths of the second photoresist pattern 168positioned on both sides of the first thin film mask pattern 164 and thefirst thin film mask pattern 164 becomes the same with a line width ofthe second photoresist pattern 168.

Then, referring to FIG. 1E, the second thin film mask pattern 166 andthe first thin film mask pattern 164 may be etched and removed insuccession to leave the second photoresist pattern 168 on the first thinfilm layer 152.

Then, referring to FIG. 1F, the first thin film layer 152 may be etchedby using the second photoresist pattern 168 as a mask, to form a thinfilm pattern 160 on the substrate 101 as shown in FIG. 1G.

The thin film pattern 160 may form a thin film pattern group PG with anadjacent thin film pattern 160 formed from the first photoresist pattern158 and the first and second thin film mask patterns 164 and 166. Inthis instance, the thin film pattern group PG may be spaced a firstdistance from an adjacent thin film pattern group PG, and the thin filmpatterns 160 in the thin film pattern group PG is spaced a seconddistance away from each other, and have the same line widths w. The thinfilm pattern 160 may have a line width of about 400˜1000 nm.

The thin film pattern 160 can be applicable to a pixel electrode 122, acommon electrode 124, a data line 104, a gate line 102, and a commonline 126 shown in FIGS. 2 and 3. In one case, the thin film pattern 160is applied to a signal line, like the data line 104, the gate line 102,and the common line 126, since the signal line has a line width reducedsmaller than the related art, increasing a pixel region as much as thereduction of the line width, an aperture is increased.

FIGS. 2 and 3 illustrate a plan view and a sectional view of a thin filmtransistor substrate having a thin film pattern formed by a formingmethod shown in FIGS. 1A to 1G, respectively.

The thin film transistor substrate may include a thin film transistorconnected to the gate line 102 and the data line 104, and a pixelelectrode 122 formed at a pixel region provided at every crossedstructure of the gate line 102 and the data line 104.

The thin film transistor causes a pixel signal supplied to the data line104 in response to a scan signal supplied to the gate line 102 to becharged and maintained at the pixel electrode 122. To do this, the thinfilm transistor includes a gate electrode 106, a source electrode 108, adrain electrode 110, an active layer 114, and an ohmic contact layer116.

The gate electrode 106 is connected to the gate line 102 such that thescan signal is supplied to the gate electrode 106 from the gate line102. The source electrode 108 is connected to the data line 104 suchthat the pixel signal is supplied to the source electrode 108 from thedata line 104. The drain electrode formed opposite to the sourceelectrode 108 with a channel portion of the active layer 114 may bedisposed there between for supplying the pixel signal from the data line104 to the pixel electrode 122. The active layer 114 may be formed atthe channel portion between the source and drain electrodes 108 and 110overlapped with the gate electrode 106 with a gate insulating film 112disposed there between. The ohmic contact layer 116 may be formedbetween the source electrode 108 and the active layer 114 and betweenthe drain electrode 110 and the active layer 114, i.e., over the activelayer 114 except the channel portion. The ohmic contact layer 116 servesto reduce electric contact resistance between the source electrode 108and the active layer 114 and between the drain electrode 110 and theactive layer 114.

The pixel electrode 122 may be connected to the drain electrode 110through a pixel contact hole 120. According to this, the pixel electrode122 may have the pixel signal supplied thereto from the data line 104through the thin film transistor. The pixel electrode 122 has a pixelhorizontal portion 122 a parallel to the gate line 102, and a pixelvertical portion 122 b extended vertically from the pixel horizontalportion 122 a.

The common electrode 124 may have the common line 126 connected theretofor receiving a common voltage through the common line 126. The commonelectrode 124 may be formed of the same material and on the same planewith the pixel electrode 122 or different material and at differentplane from the pixel electrode 122. The present disclosure will bedescribed taking the common electrode 124 and the pixel electrode 122formed at the same plane of a protective film 118 and the same materialof a transparent conductive film as an example.

The common electrode 124 may include a common horizontal portion 124 aparallel to the gate line 102, and a common vertical portion 124 bextended in a vertical direction from the common horizontal portion 124a. In this instance, the vertical common portion 124 b is formedparallel to the pixel vertical portion 122 b. Accordingly, a horizontalelectric field is formed between the pixel electrode 122 having a pixelvoltage signal supplied thereto and the common electrode 124 having thecommon electrode supplied thereto. The horizontal electric field rotatesthe liquid crystal molecules arranged in a horizontal direction betweenthe thin film transistor substrate and the color filter substrate (notshown) owing to dielectric anisotropy. And, since optical transmissivitythrough the sub-pixel regions varies with extents of rotation of theliquid crystal molecules, a picture can be produced.

FIGS. 4A and 4B illustrate a plan view and a sectional view showing amethod for forming the gate metal pattern shown in FIGS. 2 and 3 in themethod for forming a thin film transistor substrate in accordance withan exemplary embodiment of the present disclosure.

A gate metal pattern having the common line 126 and the gate line 102and the gate electrode 106 may be formed on a lower substrate 101.Formation of the gate metal pattern by a fabricating method shown inFIGS. 1A to 1G will be described taking FIGS. 5A to 5F as an example.

In detail, referring to FIG. 5A, first to third thin film layers may bestacked on the lower substrate 101 in succession by deposition, such assputtering. The first thin film layer may be a single layer of metal,such as Mo, Ti, Cu, AlNd, Al, Cr, an Mo alloy, an Al alloy, and so on,or a stack of two or more than two layers. The second thin film layer154 may be formed of an inorganic insulating film, such as SiNx or SiOx,or a columnar crystal group metal, such as molybdenum. The third thinfilm layer 156 may be formed of a non-transparent material which canshield light.

Then, referring to FIG. 5B, a first photoresist is coated on the thirdthin film layer 152, and subjected to exposure and development to form afirst photoresist pattern 158. The second thin film layer 154 may beetched after etching the third thin film layer 156 by using the firstphotoresist pattern 158 as a mask to form first and second thin filmmask patterns 164 and 166. Then, as shown in FIG. 5C, a secondphotoresist 162 may be coated between the first and second thin filmmask patterns 164 and 166. Then, full surface exposure and developmentmay be performed to remove the first photoresist pattern 158 as shown inFIG. 5D, and to pattern the second photoresist 162 under the second thinfilm mask pattern 166 to form a second photoresist pattern 168 since thesecond thin film mask pattern 166 is used as mask in the exposure anddevelopment. That is, the second photoresist pattern 168 may be formedat a region where the first and second thin film mask patterns 164 and166 positioned between the first thin film layer 152 and the second thinfilm mask pattern 166 do not overlap with each other. A sum of linewidths of the second photoresist pattern 168 and the first thin filmmask pattern 164 positioned on opposite sides with the first thin filmmask pattern 164 disposed there between may be the same with a linewidth of the second photoresist pattern 168.

Then, referring to FIG. 5E, the second thin film mask pattern 166 andthe first thin film mask pattern 164 may be removed by etching, to leavethe second photoresist pattern 168 on the first thin film layer 152. Asshown in FIG. 5F, the first thin film layer 152 may be etched by usingthe second photoresist pattern 168 as a mask, to form a gate metalpattern including the gate line 102 and the common line 126 on thesubstrate 101.

FIGS. 6A and 6B illustrate a plan view and a sectional view showing amethod for forming the semiconductor pattern and the data metal patternshown in FIGS. 2 and 3 in the method for forming a thin film transistorsubstrate in accordance with an exemplary embodiment of the presentdisclosure.

A gate insulating film 112 may be formed on the lower substrate 101having the gate metal pattern formed thereon, a data metal patternhaving a data line 104, a source electrode 108, and a drain electrode110 may be formed on the gate insulating film 112, and a semiconductorpattern having an active layer 114 and an ohmic contact layer 116 isformed overlapped with, under and along, the data metal pattern. Thesemiconductor pattern and the data metal pattern may be formed by onemask process using a slit mask or a half tone mask.

In detail, the gate insulating film 112, an amorphous silicon layer, animpurity n⁺ or p⁺ doped amorphous silicon layer, and a data metal layermay be formed on the lower substrate 101 having the gate metal patternformed thereon, in succession. And, after coating photoresist on thedata metal layer, the photoresist is exposed and developed byphotolithography with a slit mask to form a photoresist pattern having astep.

The data metal layer may be etched by using the photoresist patternhaving the step to form the data metal pattern and the semiconductorpattern under the data metal pattern.

Then, the photoresist pattern is ashed with oxygen O₂ plasma. An exposeddata metal pattern and the ohmic contact layer under the exposed datametal pattern are removed by etching by using the photoresist patternashed thus to separate the source electrode 108 from the drain electrode110 and expose the active layer 114. Then, the photoresist pattern isremoved from an upper side of the data metal pattern by stripping.

FIGS. 7A and 7B illustrate a plan view and a sectional view showing amethod for forming the protective film having a pixel contact hole and acommon contact hole in the method for forming a thin film transistorsubstrate in accordance with an exemplary embodiment of the presentdisclosure.

The protective film 118 having the pixel contact hole 120 and the commoncontact hole 128 may be formed on the substrate having the data metalpattern and the semiconductor pattern formed thereon. In detail, theprotective film 118 is deposited by CVD or PECVD on the gate insulatingfilm 112 having the data metal pattern formed thereon. The protectivefilm 118 may be formed of an inorganic insulating material the same withthe gate insulating film formed by CVD or PECVD.

Then, the protective film 118 may be patterned by photolithography andetching to form the pixel contact hole 120 and the common contact hole128.

FIGS. 8A and 8B illustrate a plan view and a sectional view showing amethod for forming the transparent conductive pattern shown in themethod for forming a thin film transistor substrate in accordance withan exemplary embodiment of the present disclosure.

A transparent conductive pattern, having a pixel electrode 122 and acommon electrode 124, may be formed on the lower substrate 101 havingthe protective film 118 formed thereon.

In detail, a transparent conductive film may be formed on the lowersubstrate 101 having the protective film 118 formed thereon bydeposition such as sputtering. The transparent conductive film is formedof indium tin oxide ITO, tin oxide TO, indium zinc oxide IZO, SnO₂, oramorphous-indium tin oxide a-ITO. Then, the transparent conductive filmmay be patterned by photolithography and etching to form the transparentconductive pattern having the pixel electrode 122 and the commonelectrode 124.

In the meantime, though the present disclosure has been described takinga case in which the thin film pattern of the present disclosure isapplied to a thin film transistor substrate as an example, besides this,the present is also applicable to a flat display device, such as a colorfilter substrate of a liquid crystal display device, organic electroluminescence display device, three dimensional image display device, andelectro-ink type display device.

As has been described, the method for forming a thin film pattern and aflat display device having the same of the present disclosure has thefollowing advantages.

The present disclosure enables to form a micron pattern with a sizebelow 1 μm by using three thin film layers having an uppermost layer ofa non-transparent material. The micron pattern is applicable to apattern which requires a high resolution. And, if full surface exposureis conducted by using the uppermost layer of a non-transparent materialin the three thin film layers, the second photoresist pattern is formedon the substrate in self-alignment without a separate alignment step.

It will be apparent to those skilled in the art that modifications andvariations can be made in the present disclosure without departing fromthe spirit or scope of the disclosures. Thus, it is intended that thepresent disclosure covers the modifications and variations of thisdisclosure provided they come within the scope of the appended claimsand their equivalents.

What is claimed is:
 1. A method for forming a thin film pattern,comprising the steps of: forming first, second, and third thin filmlayers on a substrate in succession; forming a first photoresist patternon the third thin film layer; patterning the second and the third thinfilm layers by using the first photoresist pattern as a mask to form afirst and a second thin film mask patterns having line widths differentfrom each other; forming a second photoresist pattern at a regionpositioned between the first thin film layer and the second thin filmmask pattern where the first and the second thin film mask patterns donot overlap with each other; removing the first and the second thin filmmask patterns; and patterning the first thin film layer by using thesecond photoresist pattern as a mask to form a thin film pattern,wherein the step of forming a second photoresist pattern includes thesteps of: forming a second photoresist on the substrate having the firstand the second thin film mask patterns formed thereon to cover a side ofthe first thin film mask pattern and the first thin film layer, andexposing and developing a full surface of the first photoresist patternand the second photoresist to remove the first photoresist pattern andpatterning the second photoresist by using the second mask pattern as amask.
 2. The method as claimed in claim 1, wherein the second thin filmlayer is formed of an inorganic insulating film or a columnar crystalgroup material, and the third thin film layer is formed of anon-transparent material which shields a light.
 3. The method as claimedin claim 2, wherein the columnar crystal group material is molybdenum.4. The method as claimed in claim 1, wherein the first thin film maskpattern has an obtuse or rectangular taper angle.